iphone 3Gs error message: " this accessory is not made to work with iphone"

I had this error mesasge popping up randomly:" this accessory is not made to work with iphone", and it continues saying something about changing to air plane mode.

But it was fixed just right when i connected the charger ... i am gussing it was caused by sand stuck in the hole where i plug the charger ... I am afraid it comes again, i just think when something weird pops up once, it is most definitely coming again someday

I bought my iphone with a deal of one year warranty, is it possible they will replace it for me if the warranty is not valid any more ?

Moreover, i jailbreaked my iphone, so do i loose my warranty that way ?

the wrong what? ... if u mean the wrong charger, it is the one that came in the box with the iphone which was closed ... so it is the right one ...